Third Type of Human Fat Discovered and its Beige

A new survey has found that more than half of Australians these days have become overweight or obese.
Reuters

People are normally known to have two types of fat, white and brown. Now scientists have discovered a third type of fat cell called beige fat. They claim the discovery will help fight obesity.

According to the discovery published in Cell Journal, scientists from Harvard Medical School have found that just triggering the beige fat can help combat obesity and diabetes.

"We've identified a third type of fat cell," said Bruce Spiegelman, researcher at Harvard Meigeedical School. "There's white, brown and now there is this third type that is present in most or all human beings."

The discovery was made while studying mice fat cells. During the study, scientists found that beige fat exists between white fat and brown fat. While analysing the fat cell, scientists found that beige fat has low levels of uncoupling protein 1 (UCP1), a key ingredient for burning energy and generating heat, similar to white fat. But the beige cells also have a remarkable ability to ramp up their UCP1 expression, turning on an energy-burning programme that is equivalent to that of classical brown fat.

Scientists also found that beige fat responds to irisin hormone released during any physical exercise; the hormone helps convert white fat into brown fat. The brown fat converts the calories into heat.

"Beige cells respond to a hormone known as irisin to turn on the energy-burning programme. That's particularly notable because irisin is released from muscle with exercise, and it is responsible for some of the benefits that physical activity brings," said Spiegelman.

"Irisin might just be the long-sought treatment aimed to increase those coveted energy-burning fat cells. In addition to the therapeutic potential, the new findings might also lead to new and better ways to characterise important differences amongst people in the numbers of beige cells they carry," he added.

Earlier, researchers had claimed that brown fat only existed in babies but the new study finds that adults too have it.

"The energy-burning brown fat found amongst energy-storing white fat in adults wasn't exactly the classical brown fat you see in babies. Babies' brown fat arises from muscle, but these adult brown fat cells arise from the 'browning' of white fat," said Spiegelman.